The new App Store guidelines introduced by Apple on Thursday present a much clearer idea of what Apple wants developers creating. Up until now, the dos and don'ts of getting apps onto the App Store have largely been guesswork, in part from culling the iOS Developer Program License Agreement, as well as seeing the successes and failures of other developers.

But what makes the new rules so interesting is that quite a few of them call out behaviors or practices by application developers that are quite clearly being used in apps that are still in the store. Will these apps be pulled, made to conform to the new rules, or simply grandfathered in as having gotten through Apple's approval process before they knew better?

One of the new rules that may end up as a thorn in the side of a handful of developers is 11.2 in the purchasing and currencies section. This stipulates that "apps utilizing a system other than the In App Purchase API (IAP) to purchase content, functionality, or services in an app will be rejected." This goes squarely against the system developer TapJoy has put in place with its apps, including the hit title Tap Defense. Titles within the TapJoy network employ a "favor" system that lets players unlock additional features or levels by completing various tasks, be it rating the title in the App Store, or downloading other networked games.

On top of these small actions, TapJoy has an "offers" section that goes one step beyond and will award a much larger number of favor points to users who sign up with third-party services. At the time of this writing these include a subscription with video game by mail rental service GameFly, or subscribing to Disney's Movie Club. Assuming Apple begins to police apps that are not using IAP, TapJoy may inevitably end up having to remove its rewards system in favor of adopting Apple's.

Another company that could run into trouble with one of the new rules is Ngmoco, the makers of many hit iOS titles including We Rule, Eliminate, and the Touch Pets series. Rule 11.9 says that "apps containing 'rental' content or services that expire after a limited time will be rejected." One of its titles, called Godfinger, sells power-ups that only work for a limited amount of time--typically one day. Currently that's an extension on how much "mana" users can accumulate at any given time, a self-replenishing in-game resource that can be used to re-energize workers and buildings. Prior to that, there was a way to improve how long workers kept their energy up, though it's since been removed.

In either case, Ngmoco could be exempt from the new rule since its system has users buying these items with in-game currency, which is doled out to users through gameplay, though can also be purchased in allotted units through IAP instead of using IAP for those specific features.

Hardware hackery
What will certainly be the most interesting thing to watch for is whether Apple decides to get rid of the handful of high-profile apps that have made use of the iPhone hardware in ways that push the device.

Two new items under the "damage to device" subsection say that "apps that encourage users to use an Apple device in a way that may cause damage to the device will be rejected," as well as any apps that "rapidly drain the device's battery or generate excessive heat."

Sound familiar? The app Pocket Heat by HAL Apps made waves when it was released back in January. The app used several of the iPhone's internal sensors like the GPS receiver and the accelerometer to run the device to the point of it heating up. Though it was cute, Apple ended up making the developers remove the functionality, leaving the app as little more than a grill simulator.

There's also Blower, which popped up in the App Store in late November of last year, which uses the iPhone's speaker at a particular frequency to create airflow. Users are encouraged to turn up the volume as loud as possible to achieve a more potent effect. The developer also has two other apps called Blow Soccer and Magic Mover, which play off the same idea. In Magic Mover's case, it eschews the speaker in favor of strategic vibration that will move the iPhone in a particular direction. Presumably these features tap into both the battery draining and damage sections of the new rules.

Blood, guts, and sexy pictures
Arguably two of the most controversial items within the new guidelines are the violence and pornography sections. These go into detail on how much gore one can include, as well as very stringent stipulations on weaponry and how far violence can go. The pornography section is slightly tamer, though like many other items within the guidelines, open to interpretation.

On the violence front, games that are bound to run into problems with the new rules are pretty much any shooting game, though particularly hunting and sniping games. Rule 15.1 says that "apps portraying realistic images of people or animals being killed or maimed, shot, stabbed, tortured, or injured will be rejected."

Within that context, titles such as Deer Hunter 3D or Deer Hunter: African Safari stand to be removed, given that the primary objective is to hunt down deer with various weapons, often employing different kill animations depending on where you end up hitting the animal. The same goes with sniping games like the popular Sniper vs. Sniper, iSniper 3D, and Silent Scope, the last of which involves your victims falling off of buildings after being shot.

A screen of iSniper 3D clearly depicting a bloody headshot, something that is now expressly prohibited within iPhone apps.
Triniti Interactive Limited

Another interesting tidbit within the section on violence is that "'enemies' within the context of a game cannot solely target a specific race, culture, a real government or corporation, or any other real entity." For a number of games from big companies like Gameloft, including titles like the Brothers In Arms and the Modern Combat series, this poses a fairly serious hurdle, as those games have you fighting Nazis or terrorist groups in the Middle East. Does this mean those games are going to get pulled, too, or that the developers be forced to change the existing enemies to some nondescript group? That's hardly fostering of a franchise, or historical battles that have become the mainstay of shooter games on other gaming platforms.

The subject of pornography is a little more ambiguous, and one of the shortest sections in Apple's document:

18.1 Apps containing pornographic material, defined by Webster's Dictionary as "explicit descriptions or displays of sexual organs or activities intended to stimulate erotic rather than aesthetic or emotional feelings" will be rejected.

18.2 Apps that contain user-generated content that is frequently pornographic (ex., "Chatroulette" apps) will be rejected.

Though the first item is pretty straightforward, it's the second one that can be considered problematic. Apple calls out the Chatroulette video service, which never actually ended up on the iPhone as an app; however, back in July an app called iChatr grabbed headlines for emulating its instant video chat with strangers experience using Apple's FaceTime feature. It was pulled within days after users began using it to expose themselves. Whether a developer can anticipate or protect against such things is often something that occurs post-release, though what really matters is that the app made it through the approval process in the first place.

There's a lot to take in with all these new rules. Even though many of them were to be expected, quite a few bring up questions about content that has already been approved and has sold well in the App Store. Apple makes a particular note about the approval guidelines being a "living document that will evolve as we are presented with new apps and situations," though the question remains whether Apple will let some apps that have already made it through continue to live on.